This invention relates to a reheat furnace for metallic workpieces, and more particularly to apparatus for anchoring workpiece-support skids to a foundation for resisting longitudinal movement of the skids while workpieces are advanced on the skids through the furnace.
Although not so limited, the present invention is particularly useful for anchoring skid members of a pusher-type reheat furnace used to heat billets, blooms or slabs. The workpieces are advanced through the furnace for heating therein by a pusher mechanism at the charging end or side of the furnace to engage a newly-introduced workpiece. A cold workpiece is pushed into the furnace against a continuous line of workpieces that abut in a side-by-side relation. A heated workpiece is discharged from the opposite end of the furnace in any one of various manners such as sliding on skids by gravity through a door opening onto a roller table or a workpiece-extracting device. A furnace may embody a construction to permit pushing of a heated workpiece through a side-door opening onto a mill table by a suitable mechanism. After heating in the furnace, the workpiece is advanced by a roller table to a rolling mill or other apparatus to process the workpiece.
In a reheat furnace of the above-described type, and in other furnace constructions, each of a plurality of skid members must be anchored against longitudinal movement and supported to carry a workpiece or article while it is advanced through the furnace. The skids must be anchored in a way to resist the forces imparted to the skids due to the sliding motion of the workpieces therealong. Such furnaces are subject to the problem, which is particularly acute in a reheat furnace for slabs, of stretching and loosening up of the skids. Premature failure, due to excessive vibration of the skids, will occur should they become loose. At the same time, maintenance costs become excessive because of the loss of insulation which cannot be retained on the loose skids. Thus, the loss of insulation substantially increases the heat loss and the fuel requirement by the furnace. Usually, the skids which sometimes take the form of pipes for a flow of coolant medium are cooled to prevent overheating. A turnbuckle is sometimes incorporated as part of the anchoring system to adjust the skids. However, in actual practice it is practically impossible to adjust these turnbuckles for tightening the skids after operation of the reheat furnace for a length of time. The turnbuckles must be situated at a site having a particularly hostile environment since they must be located at the entry side of the furnace and usually below machinery of the pusher and roller tables for supplying workpieces to the furnace. The size of the turnbuckle is usually relatively large since in the anchoring system, rod members having a diameter of 3-4 inches must be joined together by the turnbuckle. One rod member extends to the foundation and another rod member extends to the furnace skid. Adjusting and tightening of a turnbuckle for the skid member is usually performed while the skids are heavily loaded due to the weight of the workpieces, thus requiring the development of a substantially large force. In a slab reheat furnace, for example, each skid is typically loaded in excess of 150,000 pounds. Thus, a turnbuckle is not practical and is usually inoperative for its intended purpose.